Heat dissipation device

ABSTRACT

This disclosure provides a heat dissipation device configured to be in thermal contact with a heat source. The heat dissipation device includes a heat dissipation body and a cover plate. The heat dissipation body has at least one vertical channel. The heat dissipation body is configured to be in thermal contact with the heat source. The cover plate includes a first layer and a second layer that are stacked on each other. The first layer is stacked on the heat dissipation body and covers the at least one vertical channel. A thermal conductivity of the first layer is larger than a thermal conductivity of the second layer. The cover plate has at least one first through hole penetrating through the first layer and the second layer and connecting to the at least one vertical channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 108119018 filed in Taiwan, R.O.C. onMay 31, 2019, the entire contents of which are hereby incorporated byreference.

TECHNICAL FIELD

The disclosure relates to a heat dissipation device, more particularlyto a heat dissipation device having at least one vertical channel.

BACKGROUND

In recent years, electronic devices, such as laptop computers, tabletcomputers, and cellular phones, have become compact and slim yetpowerful, so internal heat dissipation devices for such electronicdevices have become smaller than before. Therefore, it is alwaysdesirable to find a way to effectively cool the electronic devices bysmall sized heat dissipation devices.

In general, the conventional heat dissipation device includes a copperor aluminum made base plate and heat dissipation fins disposed on thebase plate. The heat dissipation device has a limited thermal contactsurface, so it is known that increasing the flow rate of working fluidflowing over the heat dissipation device is one of the critical factorsto improve the cooling efficiency of the heat dissipation device. Forexample, some use a fan to increase the flow rate of working fluid, buta slim and compact electronic device does not have an enough space foraccommodating a fan, so such electronic device still uses naturalconvection for cooling. Therefore, the disclosure seeks to overcome oneor more of the above disadvantages.

SUMMARY

The disclosure relates to a heat dissipation device for improving thecooling efficiency of heat dissipation component under naturalconvection.

An embodiment of the disclosure provides a heat dissipation deviceconfigured to be in thermal contact with a heat source. The heatdissipation device includes a heat dissipation body and a cover plate.The heat dissipation body has at least one vertical channel and isconfigured to be in thermal contact with the heat source. The coverplate includes a first layer and a second layer that are stacked on eachother. The first layer is stacked on the heat dissipation body andcovers the at least one vertical channel. A thermal conductivity of thefirst layer is larger than a thermal conductivity of the second layer.The cover plate has at least one first through hole penetrating throughthe first layer and the second layer and connecting to the at least onevertical channel.

Another embodiment of the disclosure provides a heat dissipation deviceconfigured to be in thermal contact with a heat source. The heatdissipation device includes a heat dissipation body and a cover plate.The heat dissipation body has at least one vertical channel and isconfigured to be in thermal contact with the heat source. The coverplate is stacked on the heat dissipation body and covers the at leastone vertical channel. A thermal conductivity of the heat dissipationbody is larger than the thermal conductivity of the cover plate. Thecover plate has at least one first through hole connecting to the atleast one vertical channel.

Still another embodiment of the disclosure provides a heat dissipationdevice configured to be in thermal contact with a heat source. The heatdissipation device includes a heat dissipation body and a heatinsulation film. The heat dissipation body includes a first thermallyconductive plate, a second thermally conductive plate and a plurality offins that are integrally formed with one another. The plurality of finsare located between the first thermally conductive plate and the secondthermally conductive plate. The first thermally conductive plate, thesecond thermally conductive plate and the plurality of fins form aplurality of vertical channels therebetween. The first thermallyconductive plate is configured to be in thermal contact with the heatsource. The second thermally conductive plate has a plurality of firstthrough holes connecting to the plurality of vertical channels. The heatinsulation film has a plurality of second through holes and is stackedon a side of the second thermally conductive plate facing away from thefirst thermally conductive plate. The plurality of second through holesare respectively connected to the plurality of vertical channels via theplurality of first through holes.

According to the heat dissipation devices discussed above, due to thecomposite material of the cover plate or the heat dissipation body, orthe thermal insulation part, the amount of heat transferred to the fluidinside the vertical channels will be more than that transferred to thefluid outside the vertical channels, such that the fluid inside thevertical channels will flow faster than the fluid outside the verticalchannels. According to the Bernoulli's equation, the higher velocity ofthe fluid inside the vertical channels will result in a pressure lowerthan that in the space outside the vertical channels, and which willdraw the air outside the vertical channels into the vertical channels toincrease the flow rate of the fluid in the vertical channels. Therefore,during the operation of the heat source, the flow rate of the fluidflowing through the vertical channels can be increased. The increasedflow rate of the fluid in the vertical channels can help improve thecooling efficiency of the heat dissipation device to the heat sourceunder natural convection.

The above embodiments and following detailed descriptions are consideredas examples of the application of the principles of the disclosure,which help to facilitate comprehension of the claims but are not limitedto any specific details of these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a heat dissipation device according to afirst embodiment of the disclosure;

FIG. 2 is an exploded view of the heat dissipation device in FIG. 1;

FIG. 3 is a planar view of a cover plate in FIG. 2;

FIG. 4 is a cross-sectional view of the heat dissipation device in FIG.1;

FIG. 5 is a cross-sectional view of a heat dissipation device accordingto a second embodiment of the disclosure;

FIG. 6 is a cross-sectional view of a heat dissipation device accordingto a third embodiment of the disclosure;

FIG. 7 is a cross-sectional view of a heat dissipation device accordingto a fourth embodiment of the disclosure;

FIG. 8 is a cross-sectional view of a heat dissipation device accordingto a fifth embodiment of the disclosure;

FIG. 9 is a perspective view of a heat dissipation device according to asixth embodiment of the disclosure;

FIG. 10 is a cross-sectional view of the heat dissipation device in FIG.9; and

FIG. 11 is a cross-sectional view of a heat dissipation device accordingto a seventh embodiment of the disclosure.

DETAILED DESCRIPTION

Please refer to FIG. 1 and FIG. 2. FIG. 1 is a perspective view of aheat dissipation device according to a first embodiment of thedisclosure. FIG. 2 is an exploded view of the heat dissipation device inFIG. 1.

This embodiment provides a heat dissipation device 10 configured to bein thermal contact with a heat source 11. The heat dissipation device 10includes a heat dissipation body 110 and a cover plate 120. The heatdissipation body 110 may include copper and have a thermal conductivityof approximately 390 W/mk to 401 W/mk. The heat dissipation body 110 isconfigured to be in thermal contact with the heat source 11.

The heat source 11 may be a central processing unit, battery or lightemitting diode. The heat dissipation body 110 has at least one verticalchannel S. In detail, the heat dissipation body 110 includes a base 111and a plurality of heat dissipation fins 112. The heat dissipation fins112 protrude from the base 111, and every two adjacent heat dissipationfins 112 are spaced apart by a vertical channel S. As can be seen, theheat dissipation body 110 has a plurality of vertical channels S, but itis noted that the disclosure is not limited to the quantity or size ofthe vertical channels S.

Each vertical channel S has an extension direction E parallel to avertical direction V, where the vertical direction V is the direction ofgravitational force. However, the disclosure is not limited thereto; inother embodiments, the extension direction of the vertical channels mayhave an acute angle to the vertical direction. It is noted that theextension direction of the vertical channels is not limited to beparallel to or has an acute angle to the vertical direction as long asit is not perpendicular to the vertical direction.

The cover plate 120 is stacked on the heat dissipation fins 112, and thecover plate 120 and the base 111 are respectively located on twoopposite sides of the heat dissipation fins 112. The cover plate 120 maybe connected to the heat dissipation fins 112 by press fit, riveting orwelding. In the case that the cover plate is connected to the heatdissipation fins by press fit, the cover plate may have slotsrespectively for the heat dissipation fins to mount on the cover plate.The cover plate 120 may have a thickness T ranging approximately between1 millimeter and 5 millimeters. In detail, the cover plate 120 includesa first layer 121 and a second layer 122. The first layer 121 mayinclude copper and have a thermal conductivity of approximately 390 W/mkto 401 W/mk. The first layer 121 is stacked on the heat dissipation body110 to cover the vertical channels S. The second layer 122 may includeplastic and have a thermal conductivity lower than 1 W/mk. The secondlayer 122 is stacked on a side of the first layer 121 facing away fromthe heat dissipation body 110, that is, the first layer 121 is locatedbetween the heat dissipation body 110 and the second layer 122. In thisembodiment, the thermal conductivity of the first layer 121 is at leastone hundred times higher than that of the second layer 122, but thedisclosure is not limited thereto. In other embodiments, the thermalconductivity of the first layer may be at least twenty times higher thanthat of the second layer. In addition, in this embodiment, the firstlayer 121 and the heat dissipation body 110 have the same material, butthe disclosure is not limited thereto. In other embodiments, the firstlayer and the heat dissipation body may be made of different materialsso that the first layer may have a thermal conductivity higher or lowerthan that of the heat dissipation body.

The cover plate 120 has a plurality of first through holes O penetratingthrough the first layer 121 and the second layer 122 and connecting tosome of or all of the vertical channels S.

Please refer to FIG. 3. FIG. 3 is a planar view of a cover plate in FIG.2. In this embodiment, each first through hole O may have a diameter Dapproximately larger than or equal to 2 millimeters, and every twoadjacent second through holes O may be spaced apart by a gap Gapproximately larger than or equal to 3 millimeters. It is noted thatthe diameter D and gap G are one of the ways to explain the empty spacesin the cover plate 120. The porosity can be another way to explain theempty spaces in the cover plate 120, where the porosity is thepercentage of empty space in the cover plate 120 and, in this or someother embodiments, can be defined as the ratio of the total volume ofthe empty spaces divided by the total volume of the cover plate. In thisembodiment, the porosity of the cover plate 120 may be approximatelyranging between 20% and 50%.

In addition, in this embodiment, the first through hole O is a circularthrough hole, but the disclosure is not limited to the shape of thesecond through hole. For example, in other embodiments, the firstthrough hole may be a square, triangular, or hexagonal through hole.

Please refer to FIG. 4. FIG. 4 is a cross-sectional view of the heatdissipation device in FIG. 1. The base 111 of the heat dissipation body110 is in thermal contact with the heat source 11 so that heat generatedby the heat source 11 will be transferred to the heat dissipation body110 and thus will heat the fluid F1 in the vertical channels S, therebycausing the fluid F1 to flow upwards. Within a short time period, theheat generated by the heat source 11 will be transferred to the coverplate 120 via the heat dissipation body 110 and thus heating the fluidF2 outside the cover plate 120, thereby causing the fluid F2 to flowupwards. Since the first layer 121 has a higher thermal conductivitythan the second layer 122, more heat will be transferred towards thefluid F1. As a result, the fluid F1 will flow faster than the fluid F2.According to the Bernoulli's equation, if the velocity increases, thenthe pressure decreases. Therefore, the higher velocity of the fluid F1will result in a pressure in the vertical channels S lower than that inthe space in which the fluid F2 flows, causing the air outside thevertical channels S to flow into the vertical channels S (e.g., fluid F3shown in FIG. 4). Such movement of air is known as the stack effect.

Accordingly, during the operation of the heat source 11, the flow rateof the fluid flowing through the vertical channels S can be increasedwith the help of the first through holes O of the cover plate 120 andthe different thermal conductivities between the first layer 121 and thesecond layer 122. The increased flow rate of the fluid in the verticalchannels S can help improve the cooling efficiency of the heatdissipation device 10 to the heat source 11 under natural convection.

It is noted that the flow rate of the fluid F3 will be increased if anyone of the porosity of the cover plate, the diameter D of the firstthrough holes O, and the gap G between the first through holes O meetsthe aforementioned conditions.

Please refer to FIG. 5. FIG. 5 is a cross-sectional view of a heatdissipation device according to a second embodiment of the disclosure.

This embodiment provides a heat dissipation device 20 including a heatdissipation body 210 and a cover plate 220. The heat dissipation body210 may include copper and have a thermal conductivity of approximately390 W/mk to 401 W/mk. The heat dissipation body 210 includes a base 211and a plurality of heat dissipation fins 212, and has a plurality ofvertical channels S. Every two adjacent heat dissipation fins 212 arespaced apart by a vertical channel S. The heat dissipation body 210 andthe heat dissipation body 110 of the previous embodiment are similar inconfiguration, so the heat dissipation body 210 will not be described indetail below.

The cover plate 220 is stacked on the heat dissipation fins 212, and thecover plate 220 and the base 211 are respectively located on twoopposite sides of the heat dissipation fins 212. The cover plate 220 mayinclude plastic and have a thermal conductivity lower than 1 W/mk. Thecover plate 220 is stacked on a side of the heat dissipation fins 212facing away from the base 211. In this embodiment, the thermalconductivity of the heat dissipation body 210 is at least one hundredtimes higher than that of the cover plate 220, but the disclosure is notlimited thereto. In other embodiment, the thermal conductivity of theheat dissipation body may be at least twenty times higher than that ofthe cover plate. In addition, the cover plate 220 has a plurality offirst through holes O connecting to some of or all of the verticalchannels S.

The base 211 of the heat dissipation body 210 is in thermal contact witha heat source (not shown) so that heat generated by the heat source willbe transferred to the heat dissipation body 210 and thus will heat thefluid F1 in the vertical channels S, thereby causing the fluid F1 toflow upwards. Within a short time period, the heat generated by the heatsource will be transferred to the cover plate 220 via the heatdissipation body 210 and thus heating the fluid F2 outside the coverplate 220, thereby causing the fluid F2 to flow upwards. Since the heatdissipation body 210 has a higher thermal conductivity than the coverplate 220, more heat will be transferred toward the fluid Fl. As aresult, the fluid Fl will flow faster than the fluid F2. According tothe Bernoulli's equation, if the velocity increases, then the pressuredecreases. Therefore, the higher velocity of the fluid F1 will result ina pressure in the vertical channels S lower than that in the space wherethe fluid F2 flows, thereby causing the air outside the verticalchannels S to flow into the vertical channels S (e.g. fluid F3 shown inFIG. 5).

Accordingly, during the operation of the heat source, the flow rate ofthe fluid flowing through the vertical channels S can be increased withthe help of the first through holes O of the cover plate 220 and thedifferent thermal conductivities between the heat dissipation body 210and the cover plate 220. The increased flow rate of the fluid in thevertical channels S can help improve the cooling efficiency of the heatdissipation device 20 to the heat source.

Please refer to FIG. 6. FIG. 6 is a cross-sectional view of a heatdissipation device according to a third embodiment of the disclosure.This embodiment provides a heat dissipation device 30 including a heatdissipation body 310 and a cover plate 320. The heat dissipation body310 includes a base 311 and a plurality of heat dissipation fins 312 andhas a plurality of vertical channels S. Every two adjacent heatdissipation fins 312 are spaced apart by a vertical channel S. The heatdissipation body 310 and the heat dissipation body 110 of previousembodiment are similar in configuration, so the heat dissipation body310 will not be described in detail below.

The cover plate 320 is stacked on the heat dissipation fins 312, and thecover plate 320 and the base 311 are respectively located on twoopposite sides of the heat dissipation fins 312. In detail, the coverplate 320 includes a first layer 321, a second layer 322 and a thermalinsulation part 323. The first layer 321 may include copper and have athermal conductivity of approximately 390 W/mk to 401 W/mk. The firstlayer 321 is stacked on the heat dissipation body 310 to cover thevertical channels S. The second layer 322 may include plastic and have athermal conductivity lower than 1 W/mk. The second layer 322 is stackedon a side of the first layer 321 facing away from the heat dissipationbody 310; that is, the first layer 321 is located between the heatdissipation body 310 and the second layer 322. In this embodiment, thethermal conductivity of the first layer 321 is at least one hundredtimes higher than that of the second layer 322, but the disclosure isnot limited thereto. In other embodiment, the thermal conductivity ofthe first layer may be at least twenty times higher than that of thesecond layer.

The thermal insulation part 323 is located between the first layer 321and the second layer 322. Also, the thermal insulation part 323 may bean empty space filled with air, in such a case, the thermal insulationpart 323 can be considered as an air layer and the thermal insulationpart 323 may have a thermal conductivity of approximately 0.024 W/mk,but the disclosure is not limited thereto. For example, in otherembodiments, the thermal insulation part may be a vacuum space, that is,the thermal insulation part has no air inside and can be considered as avacuum layer.

The cover plate 320 has a plurality of first through holes O penetratingthrough the first layer 321 and the second layer 322 and connecting tosome of or all of the vertical channels S.

The base 311 of the heat dissipation body 310 is in thermal contact witha heat source so that heat generated by the heat source will betransferred to the heat dissipation body 310 and thus will heat thefluid F1 in the vertical channels S, thereby causing the fluid F1 toflow upwards. Meanwhile, most of the heat in the fluid F1 is blocked bythe thermal insulation part 323 of the cover plate 320, so the heat thatis transferred to and makes the fluid F2 flow upwards is decreased.Also, because the thermal insulation part 323 is located between thefirst layer 321 and the second layer 322, and the first layer 321 hashigher thermal conductivity than the second layer 322, more heat will betransferred to the fluid Fl. As a result, the fluid F1 will flow fasterthan the fluid F2. According to the Bernoulli's equation, if thevelocity increases, then the pressure decreases. Therefore, the highervelocity of the fluid F1 will result in a pressure in the verticalchannels S lower than that in the space where the fluid F2 flows,thereby causing the air outside the vertical channels S to flow into thevertical channels S (e.g. fluid F3 shown in FIG. 6).

Accordingly, during the operation of heat source, the flow rate of thefluid flowing through the vertical channels S can be increased with thehelp of the first through holes O of the cover plate 320, the thermalinsulation part 323 and the different thermal conductivities between thefirst layer 321 and the second layer 322. The increased flow rate of thefluid in the vertical channels S can help to improve the coolingefficiency of the heat dissipation device 30 to the heat source.

Please refer to FIG. 7. FIG. 7 is a cross-sectional view of a heatdissipation device according to a fourth embodiment of the disclosure.This embodiment provides a heat dissipation device 40 including a heatdissipation body 410 and a cover plate 420. The heat dissipation body410 includes a base 411 and has a plurality of vertical channels S.Every two adjacent heat dissipation fins 412 are spaced apart by avertical channel S. The heat dissipation body 410 and the heatdissipation body 110 of previous embodiment are similar inconfiguration, so the heat dissipation body 410 will not be described indetail below.

The cover plate 420 is stacked on the heat dissipation fins 412 and thecover plate 420 and the base 411 are respectively located on twoopposite sides of the heat dissipation fins 412. In detail, the coverplate 420 includes a first layer 421, a second layer 422 and a thermalinsulation part 423. The first layer 421 may include copper and have athermal conductivity of approximately 390 W/mk to 401 W/mk. The firstlayer 421 is stacked on the heat dissipation body 410 to cover thevertical channels S. The second layer 422 may include plastic and have athermal conductivity lower than 1 W/mk. The second layer 422 is stackedon a side of the first layer 421 facing away from the heat dissipationbody 410. In this embodiment, the thermal conductivity of the firstlayer 421 is at least one hundred times higher than that of the secondlayer 422, but the disclosure is not limited thereto; in otherembodiments, the thermal conductivity of the first layer may be at leasttwenty times higher than that of the second layer.

The thermal insulation part 423 is located inside the second layer 422.Also, the thermal insulation part 423 may be an empty space filled withair, in such case, the thermal insulation part 423 can be considered asan air layer, and the thermal insulation part 423 may have a thermalconductivity of approximately 0.024 W/mk, but the disclosure is notlimited thereto; in other embodiments, the thermal insulation part maybe a vacuum space, that is, the thermal insulation part has no airinside and can be considered as a vacuum layer.

The cover plate 420 has a plurality of first through holes O penetratingthrough the first layer 421 and the second layer 422 and connecting tosome of or all of the vertical channels S.

The base 411 of the heat dissipation body 410 is in thermal contact witha heat source so that heat generated by the heat source will betransferred to the heat dissipation body 410 and thus will heat thefluid F1 in the vertical channels S, thereby causing the fluid Fl toflow upwards. Meanwhile, most of the heat in the fluid F1 is blocked bythe thermal insulation part 423 of the cover plate 420, so the heat thatis transferred to and makes the fluid F2 flow upwards is decreased.Also, because the thermal insulation part 423 is located inside thesecond layer 422 and the first layer 421 has higher heat conductivitythan the second layer 422, more heat will be transferred toward thefluid F1. As a result, the fluid F1 will flow faster than the fluid F2.According to the Bernoulli's equation, if the velocity increases, thenthe pressure decreases. Therefore, the higher velocity of the fluid F1will result in a pressure in the vertical channels S lower than that ofthe space where the fluid F2 flows, thereby causing the air outside thevertical channels S to flow into the vertical channels S (e.g. fluid F3shown in FIG. 7).

Accordingly, during the operation of the heat source, the flow rate ofthe fluid flowing through the vertical channels S can be increased withthe help of the first through holes O of the cover plate 420, thethermal insulation part 423 and the difference thermal conductivitiesbetween the first layer 421 and the second layer 422. The increased flowrate of the fluid in the vertical channels S can help improve thecooling efficiency of the heat dissipation device 40 to the heat source.

Please refer to FIG. 8. FIG. 8 is a cross-sectional view of a heatdissipation device according to a fifth embodiment of the disclosure.

This embodiment provides a heat dissipation device 50 including a heatdissipation body 510 and a cover plate 520. The heat dissipation body510 may include copper and have a thermal conductivity of approximately390 W/mk to 401 W/mk. The heat dissipation body 510 includes a base 511and a plurality of heat dissipation fins 512, and has a plurality ofvertical channels S. Every two adjacent heat dissipation fins 512 arespaced apart by a vertical channel S. The heat dissipation body 510 andthe heat dissipation body 110 of previous embodiment are similar inconfiguration, so the heat dissipation body 510 will not be described indetail below.

The cover plate 520 is stacked on the heat dissipation fins 512, and thecover plate 520 and the base 511 are respectively located on twoopposite sides of the heat dissipation fins 512. The cover plate 520includes an outer heat insulation part 521 and an inner heat insulationpart 522. The outer heat insulation part 521 may include plastic andhave a thermal conductivity lower than 1 W/mk. The outer heat insulationpart 521 is stacked on a side of the heat dissipation fins 512 facingaway from the base 511. The inner heat insulation part 522 may be anempty space filled with air, in such case, the inner heat insulationpart 522 can be considered as an air layer, and the inner heatinsulation part 522 may have a thermal conductivity of approximately0.024 W/mk, but the disclosure is not limited thereto. For example, inother embodiments, the inner heat insulation part may be a vacuum space,that is, the inner heat insulation part has no air inside and can beconsidered as a vacuum layer. The cover plate 220 has a plurality offirst through holes O connecting to some of or all of the verticalchannels S.

In this embodiment, the inner heat insulation part 522 is to improve thethermal isolation of the cover plate 520 so as to increase thedifference of heat amount between the fluid F1 and the fluid F2, therebyimproving the cooling efficiency of the heat dissipation device 50 tothe heat source.

Please refer to FIG. 9 and FIG. 10. FIG. 9 is a perspective view of aheat dissipation device according to a sixth embodiment of thedisclosure. FIG. 10 is a cross-sectional view of the heat dissipationdevice in FIG. 9.

This embodiment provides a heat dissipation device 60 including a heatdissipation body 610 and a heat insulation film 620. The heatdissipation body 610 may include copper and have a thermal conductivityof approximately 390 W/mk to 401 W/mk. The heat dissipation body 610includes a first thermally conductive plate 611, a second thermallyconductive plate 612 and a plurality of fins 613 that are integrallyformed with one another. The fins 613 are located between the firstthermally conductive plate 611 and the second thermally conductive plate612. The first thermally conductive plate 611, the second thermallyconductive plate 612 and the fins 613 form a plurality of verticalchannels S therebetween. The first thermally conductive plate 611 isconfigured to be in thermal contact with a heat source. The secondthermally conductive plate 612 has a plurality of first through holes O1connecting to some of or all of the vertical channels S.

The heat insulation film 620 has a plurality of second through holes O2.The heat insulation film 620 is stacked on a side of the secondthermally conductive plate 612 facing away from the first thermallyconductive plate 611. The second through holes O2 are respectivelyconnected to some of or all of the vertical channels S via the firstthrough holes O1. The heat insulation film 620 may be insulation paintand may have a thermal conductivity lower than 0.03 W/mk.

The first thermally conductive plate 611 of the heat dissipation body610 is in thermal contact with the heat source (not shown) so that heatgenerated by the heat source will be transferred to the heat dissipationbody 610 and thus will heat the fluid F1 in the vertical channels S,thereby causing the fluid F1 to flow upwards. Meanwhile, most of theheat in the fluid F1 is blocked by the heat insulation film 620, so theheat that is transferred to and makes the fluid F2 flow upwards isdecreased. With the help of the heat insulation film 620, more heat istransferred toward the fluid F1 than the fluid F2. As a result, thefluid F1 will flow faster than the fluid F2. According to theBernoulli's principle, if the velocity increases, then the pressuredecreases. Therefore, the higher velocity of the fluid F1 will result ina pressure in the vertical channels S lower than that of the space wherethe fluid F2 flows, thereby causing the air outside the verticalchannels S to flow into the vertical channels S (e.g. fluid F3 shown inFIG. 10).

In this case, during the operation of the heat source, the flow rate ofthe fluid flowing through the vertical channels S can be increased withthe help of the first through holes O of the second thermally conductiveplate 612, the second through holes O2 of the heat insulation film 620,and the heat insulation film 620. The increased flow rate of the fluidflowing through the vertical channels S can help improve the coolingefficiency of the heat dissipation device 60 to the heat source.

Please refer to FIG. 11. FIG. 11 is a cross-sectional view of a heatdissipation device according to a seventh embodiment of the disclosure.

This embodiment provides a heat dissipation device 70 including a heatdissipation body 710 and a cover plate 720. The heat dissipation body710 may include copper and have a thermal conductivity of approximately390 W/mk to 401 W/mk. The heat dissipation body 710 includes a firstthermally conductive plate 711, a second thermally conductive plate 712and a plurality of fins 713 that are integrally formed with one another.These fins 713 are located between the first thermally conductive plate711 and the second thermally conductive plate 712. The first thermallyconductive plate 711, the second thermally conductive plate 712 and thefins 713 form a plurality of vertical channels S therebetween. The firstthermally conductive plate 711 is configured to be in thermal contactwith a heat source. The second thermally conductive plate 612 has aplurality of first through holes O1 connecting to some of or all of thevertical channels S.

The heat insulation film 720 has a plurality of second through holes O2.The heat insulation film 620 is stacked on a side of the secondthermally conductive plate 612 facing away from the first thermallyconductive plate 611. The second through holes O2 are respectivelyconnected to some of or all of the vertical channels S via the firstthrough holes O1. The heat insulation film 620 may be insulation print,and may have a thermal conductivity lower than 0.03 W/mk. The heatinsulation film 720 includes an outer heat insulation part 721 and aninner heat insulation part 722. The outer heat insulation part 721surrounds the inner heat insulation part 722 and a thermal conductivityof the outer heat insulation part 721 is higher than that of the innerheat insulation part 722. The outer heat insulation part 721 and theinner heat insulation part 722 may respectively be insulation print andan empty space filled with air, in such case, the inner heat insulationpart 722 can be considered as an air layer, but the disclosure is notlimited thereto. In other embodiments, the inner heat insulation partmay be a vacuum space, that is, the inner heat insulation part has noair inside and can be considered as a vacuum layer.

According to the heat dissipation devices discussed above, due to thecomposite material of the cover plate or the heat dissipation body, orthe thermal insulation part, the amount of heat transferred to the fluidinside the vertical channels will be more than that transferred to thefluid outside the vertical channels, such that the fluid inside thevertical channels will flow faster than the fluid outside the verticalchannels. According to the Bernoulli's equation, the higher velocity ofthe fluid inside the vertical channels will result in a pressure lowerthan that in the space outside the vertical channels, and which willdraw the air outside the vertical channels into the vertical channels toincrease the flow rate of the fluid in the vertical channels. Therefore,during the operation of the heat source, the flow rate of the fluidflowing through the vertical channels can be increased. The increasedflow rate of the fluid in the vertical channels can help improve thecooling efficiency of the heat dissipation device to the heat sourceunder natural convection.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present invention. It isintended that the specification and examples be considered as exemplaryembodiments only, with a scope of the invention being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A heat dissipation device, configured to be inthermal contact with a heat source, the heat dissipation devicecomprising: a heat dissipation body, having at least one verticalchannel and configured to be in thermal contact with the heat source;and a cover plate, comprising a first layer and a second layer that arestacked on each other, wherein the first layer is stacked on the heatdissipation body and covers the at least one vertical channel; wherein,a thermal conductivity of the first layer is larger than a thermalconductivity of the second layer, and the cover plate has at least onefirst through hole penetrating through the first layer and the secondlayer and connecting to the at least one vertical channel.
 2. The heatdissipation device according to claim 1, wherein the thermalconductivity of the first layer is at least twenty times higher than thethermal conductivity of the second layer.
 3. The heat dissipation deviceaccording to claim 2, wherein the thermal conductivity of the firstlayer is at least one hundred times higher than the thermal conductivityof the second layer.
 4. The heat dissipation device according to claim1, wherein an extension direction of the at least one vertical channelis not perpendicular to a vertical direction.
 5. The heat dissipationdevice according to claim 4, wherein the extension direction of the atleast one vertical channel is parallel to the vertical direction.
 6. Theheat dissipation device according to claim 4, wherein the extensiondirection of the at least one vertical channel has an acute angle to thevertical direction.
 7. The heat dissipation device according to claim 1,wherein a diameter of the at least one first through hole is larger thanor equal to 2 millimeters.
 8. The heat dissipation device according toclaim 1, wherein a quantity of the at least one first through hole isplural, and every two of the first through holes that are adjacent toeach other are spaced apart by a distance larger than or equal to 3millimeters.
 9. The heat dissipation device according to claim 1,wherein a porosity of the cover plate ranges between 20% and 50%. 10.The heat dissipation device according to claim 1, wherein a thickness ofthe cover plate ranges between 1 millimeter and 5 millimeters.
 11. Theheat dissipation device according to claim 1, wherein the cover platefurther comprises a thermal insulation part located between the firstlayer and the second layer.
 12. The heat dissipation device according toclaim 11, wherein the thermal insulation part is an air layer.
 13. Theheat dissipation device according to claim 11, wherein the thermalinsulation part is a vacuum layer.
 14. The heat dissipation deviceaccording to claim 1, wherein the cover plate further comprises athermal insulation part located inside the second layer.
 15. The heatdissipation device according to claim 14, wherein the thermal insulationpart is an air layer.
 16. The heat dissipation device according to claim14, wherein the thermal insulation part is a vacuum layer.
 17. The heatdissipation device according to claim 1, wherein the at least one firstthrough hole is a circular, square, triangular or hexagonal throughhole.
 18. The heat dissipation device according to claim 1, wherein aquantity of the at least one vertical channel is plural, the heatdissipation body comprise a base and a plurality of heat dissipationfins, the plurality of heat dissipation fins protrude from the base,every two adjacent heat dissipation fins are spaced apart by one of thevertical channels, the cover plate is stacked on the plurality of heatdissipation fins, and the cover plate and the base are respectivelylocated on two opposite sides of the plurality of heat dissipation fins.19. The heat dissipation device according to claim 18, wherein the coverplate is connected to the plurality of heat dissipation fins by pressfit, riveting or welding.
 20. The heat dissipation device according toclaim 18, wherein the cover plate is adhered to the plurality of heatdissipation fins via a thermally conductive adhesive.
 21. A heatdissipation device, configured to be in thermal contact with a heatsource, the heat dissipation device comprising: a heat dissipation body,having at least one vertical channel and configured to be in thermalcontact with the heat source; and a cover plate, stacked on the heatdissipation body and covering the at least one vertical channel; whereina thermal conductivity of the heat dissipation body is larger than athermal conductivity of the cover plate, and the cover plate has atleast one first through hole connecting to the at least one verticalchannel.
 22. The heat dissipation device according to claim 21, whereinthe thermal conductivity of the heat dissipation body is at least twentytimes higher than the thermal conductivity of the cover plate.
 23. Theheat dissipation device according to claim 22, wherein the thermalconductivity of the heat dissipation body is at least one hundred timeshigher than the thermal conductivity of the cover plate.
 24. The heatdissipation device according to claim 21, wherein an extension directionof the at least one vertical channel is not perpendicular to a verticaldirection.
 25. The heat dissipation device according to claim 24,wherein the extension direction of the at least one vertical channel isparallel to the vertical direction.
 26. The heat dissipation deviceaccording to claim 24, wherein the extension direction of the at leastone vertical channel has an acute angle to the vertical direction. 27.The heat dissipation device according to claim 21, wherein a diameter ofthe at least one first through hole is larger than or equal to 2millimeters.
 28. The heat dissipation device according to claim 21,wherein a quantity of the at least one first through hole is plural, andevery two of the first through holes that are adjacent to each other arespaced apart by a distance larger than or equal to 3 millimeters. 29.The heat dissipation device according to claim 21, wherein a porosity ofthe cover plate ranges between 20% and 50%.
 30. The heat dissipationdevice according to claim 21, wherein a thickness of the cover plateranges between 1 millimeter and 5 millimeters.
 31. The heat dissipationdevice according to claim 21, wherein the cover plate further comprisesan outer heat insulation part and an inner heat insulation part, and theinner heat insulation part is located inside the outer heat insulationpart.
 32. The heat dissipation device according to claim 31, wherein theinner heat insulation part is an air layer.
 33. The heat dissipationdevice according to claim 31, wherein the inner heat insulation part isa vacuum layer.
 34. The heat dissipation device according to claim 21,wherein the at least one first through hole is a circular, square,triangular or hexagonal through hole.
 35. The heat dissipation deviceaccording to claim 21, wherein a quantity of the at least one verticalchannel is plural, the heat dissipation body comprise a base and aplurality of heat dissipation fins, the plurality of heat dissipationfins protrude from the base, every two adjacent heat dissipation finsare spaced apart by one of the vertical channels, and the cover plateand the base are respectively located on two opposite sides of theplurality of heat dissipation fins.
 36. The heat dissipation deviceaccording to claim 35, wherein the cover plate is connected to theplurality of heat dissipation fins by press fit, riveting or welding.37. The heat dissipation device according to claim 35, wherein the coverplate is adhered to the plurality of heat dissipation fins via athermally conductive adhesive.
 38. A heat dissipation device, configuredto be in thermal contact with a heat source, the heat dissipation devicecomprising: a heat dissipation body, comprising a first thermallyconductive plate, a second thermally conductive plate, and a pluralityof fins that are integrally formed with one another, the plurality offins located between the first thermally conductive plate and the secondthermally conductive plate, the first thermally conductive plate, thesecond thermally conductive plate and the plurality of fins forming aplurality of vertical channels therebetween, the first thermallyconductive plate configured to be in thermal contact with the heatsource, the second thermally conductive plate having a plurality offirst through holes connecting to the plurality of vertical channels;and a heat insulation film, having a plurality of second through holesand stacked on a side of the second thermally conductive plate facingaway from the first thermally conductive plate, wherein the plurality ofsecond through holes of the heat insulation film are respectivelyconnected to the plurality of vertical channels via the plurality offirst through holes of the second thermally conductive plate.
 39. Theheat dissipation device according to claim 38, wherein a thermalconductivity of the heat dissipation body is at least twenty timeshigher than a thermal conductivity of the heat insulation film.
 40. Theheat dissipation device according to claim 39, wherein a thermalconductivity of the heat dissipation body is at least one hundred timeshigher than a thermal conductivity of the heat insulation film.
 41. Theheat dissipation device according to claim 38, wherein an extensiondirection of the plurality of vertical channels is not perpendicular toa vertical direction.
 42. The heat dissipation device according to claim41, wherein the extension direction of the plurality of verticalchannels is parallel to the vertical direction.
 43. The heat dissipationdevice according to claim 41, wherein the extension direction of theplurality of vertical channels has an acute angle to the verticaldirection.
 44. The heat dissipation device according to claim 38,wherein diameters of the plurality of first through holes and theplurality of second through holes are larger than or equal to 2millimeters.
 45. The heat dissipation device according to claim 38,wherein the plurality of first through holes are spaced apart from oneanother by a distance that is larger than or equal to 3 millimeters andthe plurality of second through holes are spaced apart from one anotherby a distance that is larger than or equal to 3 millimeters.
 46. Theheat dissipation device according to claim 38, wherein a porosity of thesecond thermally conductive plate and a porosity of the heat insulationfilm range between 20% and 50%.
 47. The heat dissipation deviceaccording to claim 38, wherein a total thickness of the second thermallyconductive plate and the heat insulation film ranges between 1millimeter and 5 millimeters.
 48. The heat dissipation device accordingto claim 38, wherein the heat insulation film further comprising anouter heat insulation part and an inner heat insulation part, the outerheat insulation part surrounding the inner heat insulation part, and athermal conductivity of the outer heat insulation part is higher than athermal conductivity of the inner heat insulation part.
 49. The heatdissipation device according to claim 48, wherein the inner heatinsulation part is an air layer.
 50. The heat dissipation deviceaccording to claim 48, wherein the inner heat insulation part is vacuumlayer.
 51. The heat dissipation device according to claim 38, whereineach of the plurality of first through holes and each of the pluralityof second through holes are in circular, square, triangular or hexagonalshape.